I made this video from my 2019 mustang gt. Sound comes from front passenger side. Happens intermittently at low speeds and over bumps at low speeds. Seems to temporarily reduce after driving on wet roads. Sound can be generated from merely laterally rocking back and forth inside the car as seen in the video. Taking it to Ford in a couple of days.

 

On my older 06 GT, I had a clunk in the front. I had put all new A arms, new struts, just about everything you could in the suspension and steering, so a clunk was VERY annoying. The only rubber I didn't replace was the bushings for the front sway bar - they cost about 20 bucks, took about 10 minutes to install, and my problem went away. If you do not lubricate them with the included grease, apparently they will start clunking. Maybe they forgot to lubricate them at the factory???

EDIT - I just realized this post is really, really old.